Antislip device



' April 5, 1932. JOHNSON 1,852,751

ANTI'SLIP DEVICE Filed Oct. 27, 1950 fm erzz or CQNEAD 5. JOHAASON A7- TaeNEYJ' Patented Apr. 5, 1932 (UNITED STATES CONRAD B. JOHNSON, F EAU CLAIRE, WISCONSIN ANTISLI]? DEVICE This invention relatesto anti-slip devices for use on the legs of stepladders, on tripods and the like. 1

I am aware that many attempts have been s made to solve the problems in this art, of which slipping is one of the most diflicult. In order to avoid slipping, various devices have been employed such as vacuum cups, roughened-surfaces, etc., but in all, tipping and slipping of the foot piece results, or if vacuum cups are used, the material of the foot piece is weakened by formation of the unflexed or upright position;

Figure 2 1s a view similar to Figure ,1 showing the device in its flexed condition; Figure 3 is a vertical transverse section on line 33 of Figure 1; and

Figure 4; is a top plan view showing the position of the prong-traversed openings of the foot section in dotted lines.

The device provides an upper socket-providing section 1, a lower foot section 2, and

. web 3hingedly connecting the sections. The

sections have thrustsurfaces arranged laterallyof the web and normally angularly related as shown in Figure 1 to permit hinging motion of the socket member to bring the surfaces in contact. These surfaces may be considered notches which are convergent, from opposite sides toward one another and toward the web, the notch at oneside providing upper and lower surfaces respectively '45 indicated 5-6. The notch at the other side provides upper and lower surfaces respectively indicated 78. According to the'direction of rocking of thesocket section 1, the surfaces 5 and 6, or the surfaces 7 and 8 will .50 come in contact with one another.

Although it is preferable to form the device of a single piece of resilient compressible material, yet it is conceivablethat a socket member and a base member could be separately formed, and suitably hinged together by other means, and that the surfaces 6 and 7 could be formed of suitable compressible material so that the device would be compressible under the gravity action of the ladder. The device, however, can be most cheaply manufactured from a single piece of material of the kind mentioned. It will be noted that the thrust surfaces 5, 6, 7 and 8 are of substantial area so that when the surfaces are compressively broughttogether under the action of gravity of the ladder when it is in a tilted position, they substantially unite the upper and lower sections, to transfer gravity thrusts to and distribute them throughout the greater part of the area of the bottom (fif the foot, thus preventing tilting of the oot.

Although the socket member has been shown as generally of rectangular configuration, it may as well be circular or cylindrical, and the same may be said of the base piece, although it is preferable that the bottom of the base piece be of substantial area.

When the device is used on a tripod, it has been found that there is no blurring of the photographic image, due to vibration as in most other forms of tripod tips. It may be said that the surfaces of the socket and foot sections become solid or one-piece under the compressive and thrust actions of the load. Another point: The thrust surfaces extend at each side of the web a substantial distance therebeyond. It will be further noticed that the area of these surfaces is substantially greater than the horizontal cross-sectional area of the web and that when the device is attached to the leg of a ladder the long dimension of the web is parallel with the rung the traction or anti-slipping effects of the bottom surface of the foot, with the support.

As herein shown, and as indicated by lines D, E, the top surface of the notch on one side and the bottom surface of the notch on the other are substantially coplanar, and cross on a-center line F. The preferable notch angle is*3(). The width of the'fillet or'we'b is substantially one-fourth of the all-over length of the socket element. It will be understood, of course, that these statements arenot intended as limitations of the invention, inasmuch as they only represent the practice at present found most advisable. The object attained by such a design is a maximum of web or'fi'llet strength, combined with: maximum: of bendability and compressibility in the hinging; area.

The weight of the stepladder and the weight. of the load thereon are compressive- 1y transferred to the flat floor-engaging portion' of the foot, and inasmuch as the foot 'is formed of a substantially solid piece of materia'has distinguished from material which has atbottom. cupped surface, there is always a. substantial surface contact which positivelyiprevents slipping. This compressive contact of the surfaces56, 78, (particularly when the'ladder is loaded, as when a person mounts it)v is a very important feature. of the inventionbecause there is formed a substantially solidbase on that side, with the. load distributed substantially over the entire bottom surface of the foot, due to thrusts in a vertical direction, and parallel with the line F"F,.and.also along. line G'G axially of the ladder, which line crosses the line F--F, distributingvthe load as aforesaid.

Anothervaluable feature of the inventioirrelates to the anti-slip means for the foot adapted for use in conjunction with ice or oile'olafloors. This device is adapted to operate whenever the article supportedassumes an'aiigular position with respect to the vertical. The'action is such that a spike is caused to project beyond the bottom'oftlie foot and into'the slippery surface, This means may be operable by the upper section 1 when rocked; and is herein so constructed as to be: automatically projected through the bottom of the lower section 2. This device has herein the form of: a U-shaped element providing a cross piece 15, prong 16, andv a prong17. The prongs traverse the bottom 18 of the upper: section, openings 19 being provided for this purpose. The bottom section 2is also provide'd'with openings 20 which are substanti'all y larger thanthe prongs so that: when theelement 1 is rocked, the element 1 7 may ride outwardly indirection of the arrow B. Thenum'eral indicates the bottom of a stepladderor a tripod, and when the prong deviceds used, thebott'om 26 engages the top 'surfa'ce27 of thec'ross piece 15* so that thrust is applied'throughthe element 15 to-the bot= tom 18 of the socket. The end portions of the bottom of the cross-piece 15 are, in this instance, engaged against the corresponding surfaces of the inner surface of the bottom 18. The contact actions of the surfaces 7 and 8 and of the prong 16 are shown in Figure 2, and itwill be understood that the same action takes place with: the surfaces 5 and 6 and prong 17 when the socket 1 is tilted in the opposite dlrectlon. The spikes merely provide means which are automaticaly projected when the top surface is rocked for the purpose set'forth.

Normally, as shown in Figure 1, the ends of the spikes do not project beyond the bottom of the ba'se,.but just. as soona/sthe socket IIlOVGSEtO some angle laterally of the vertical, one of the prongs is caused to move tobec'ontacted. with. t-he-= slippery surface The. device is cast from rubber, andzithassubstantially plane-faced notches extending inwardly from opposite sides. an equal distance, leavingor defininga centrally disposed flexible and. compressible Web or. filletwhich permits free hinging. action, to. bring the faces. of corresponding notchesv against one another when: the socket-portion is: rocked, the arrangement being such that when the ladder is loaded, these-surfaces are putvunder compression. Thus at whatever angle the ladder assumes,a compression thrust takes place, which is distributed substantially throughout the entire area of the'foot. portion.

I. claim. as my invention:

1. A device of the class: described having an upper socket-providing section, a-lower foot. section, and an elongated web of resilient. compressible material hingedly connecting the sections, saidsections at eachv opposite side of the web providing upper and lower flat. surfaces, the former adapted toineet the latter as. a: stop when saidlupperv section is rocked.

2. A device of theclassdescribed for-med fromv elastic and compressible. material, and having an upper. socket-providing section, a lower. foot. section, and a'web'hingedly connecting: said sections, said: upper and lower sections havingithrust surfaces arranged laterally of the web andnormally angularly related to permit hinging motionofthe'isocket member to bring. the'surfaces in contact.

3. A device of: the class d'escribedmoinposed of a single piece of' resilient compressible material having notches extending inwardly fromopposite sides to define andiprovide =up"- per-and lower sections connected. by a web, said notches being convergent toward: one another and toward the web andiproviding upper and I lower surfaces-which are adapted to mee'twhen the. upper seetionlis rookedi and which" are?- adapted to I be r compressively engaged, WhenJlo'a'dis applied: by an object supported by the'upper section;

4. A device of the class described composed of a single piece of resilient compressible material having notches extending inwardly from opposite sides to define and provide upper and lower sections connected by a web, said notches being convergent toward one another toward the web and providing upper and lower surfaces which are adapted to meet when the upper section is rocked, and

adapted to be compressively engaged when load is applied by an object supported by the upper section, and means operable by the upper section and adapted when said section is rocked to be automatically proj ected through the bottom of the lower section to engage a support and prevent slipping of the device.

5. A device of the class described composed of a single piece of resilient compressible material having notches extending inwardly from opposite sides to define and provide upper and lower sections connected by a web, said notches being convergent toward one another and toward the web and providing upper and lower surfaces which are adapted to meet when the upper section is rocked, and adapted to be compressively engaged when load is applied by an object supported by the upper section, and means operable by 80 the upper section as it rocks and providing prongs adapted to be alternately projected to engage a support and secure the device against slipping.

6. A device of the class described formed 85 from elastic compressible material and having an upper socket-providing section, a lower flat-bottomed foot section, and a web portion hingedly connecting said sections cen- 1 trally, said upper and lower sections having flat thrust surfaces of substantial area arranged at each side of the web and said sur faces being angularly related to permit hinging motion of the socket section to bring the surfaces into contact, to be compressively engaged when load is applied by an object supported in the socket section, said web being elongated in a direction perpendicular to the direction of bend, and means carried by the socket section and extending through the foot section and including spikes adapted to be automatically projected when the top section is rocked to prevent slipping of the base on a slippery support.

In witness whereof, I have hereunto set 5 my hand this 23 day of Oct. 1930.

CONRAD B. JOHNSON. 

